[FIX] sale_timesheet : unlink timesheet from invoice when deleting

invoice line

Steps:
- Create 2 service products with "Invoicing based on timesheet" & " Create a task in sales order's project"
- Create a SO with both products > confirm
- Add hours to both tasks
- Create invoice > remove one invoice line > Save

Issue:
- The removed invoice line is still appearing in the Timesheet stat button

Cause:
- account_analytic_line.timesheet_invoice_id is set to the invoice when the invoice is created
- It is not reset to False when the line is removed from the invoice

Fix:
- Reset it to False when the move the line is removed from invoice

opw-2668814

closes odoo/odoo#81145

Signed-off-by: Laurent Stukkens (ltu) <ltu@odoo.com>